Stochastic Simulations For Prediction Of NVH Performance And Robustness Due To Variability In Wheel/Tire Imbalance Forces

NVH responses are often 'Error States', which do not tend to happen in the similar levels on all vehicles. Hence NVH responses always show variation and looks like a 'scatter' between individual vehicles with nominal identical designs. Also, NVH responses are complex having non-linear relationship with design parameters resulting in large changes in NVH responses with small inevitable design variation and vice-versa. In recent times, due to substantial reduction in lead time to production, implementing methods to account for variation during the design process to secure acceptable NVH levels is critical to avoid high fixation cost during testing stage or total failure of vehicle's NVH performance. Traditionally, imbalance in rotating components like drivetrain and wheels can introduce major variations in the excitation forces which results in NVH performance issues. The purpose of this paper is to predict and characterize the variation in NVH responses due to imbalances in the wheels, tire non uniformity and brake judder, and propose a methodology to account for the variabilities from these sources. A stochastic simulation methodology has been proposed to vary the forcing function emerging from these imbalances and predict the vehicle NVH responses. The individual and interactive effects of these variabilities on the NVH performance along with failure assessment to obtain a robust design are discussed in detail. The focus is more on the application of a process that encompasses objective setting, design synthesis, and NVH performance achievement using simulation predictions on a real-life project.